Connector connecting bolt, connector and connector assembly

Abstract

A bolt ( 10 ) includes a flange ( 14 ) that bulges radially out near a head ( 12 ) at one axial end. The flange ( 14 ) contacts a second connector ( 60 ) at a proper connection to prevent further tightening. A stepped recess ( 16 ) is located between the head ( 12 ) and a screw portion ( 13 ), and is recessed sufficiently to fracture when an excessive tightening torque is applied. A retaining groove ( 18 ) is located between the stepped recess ( 16 ) and the screw portion ( 13 ) and is recessed radially inwardly and receives a retaining ring ( 80 ) for preventing detachment of the bolt ( 10 ) from a first connector ( 40 ) by contacting the first connector ( 40 ) before connection. Seal grooves ( 15 ) are located between the stepped recess ( 16 ) and the flange ( 14 ) for receiving seals ( 30 ) to be held in close contact with the first connector ( 40 ) in a liquid-tight manner at the time of proper connection.

What is claimed is: 
     
       1. Connector connecting bolts, each of the connector connecting bolts being mountable in a first connector and being connectable to a mating second connector, each of the connector connecting bolts comprising:
 a head at or near a first axial end part; 
 a screw portion at or near a second axial end part spaced from the first axial end part in an axial direction of the connector connecting bolt; 
 a flange bulging radially out adjacent to the head and being engageable with the first connector when properly connected to prevent any further tightening of the bolt; 
 at least one stepped recess between the first axial end part and the screw portion, and being recessed radially inwardly a sufficient amount to be fractured when an excessive tightening torque is applied; 
 at least one retaining groove between the stepped recess and the screw portion in an axial direction and recessed radially inward for receiving a retaining member that contacts the first connector before connection of the first and second connectors for preventing detachment of the bolt from the first connector; and 
 at least one seal groove between the stepped recess and the flange in the axial direction and recessed radially inward for receiving at least one seal to be held in close contact with the first connector in a fluid-tight manner at the time of proper connection, wherein a thickness of the flange in the axial direction is larger than a width of the seal groove in the axial direction so that the flange of one of the bolts is not insertable into the seal groove of another of the bolts for preventing damage to the seal groove. 
 
     
     
       2. The connector connecting bolts of  claim 1 , wherein each of the connector connecting bolts further comprises at least one auxiliary recess adjacent an axial end of the stepped recess and between the stepped recess and the screw portion and recessed radially inward, the auxiliary recess being engageable by a jig if the stepped recess is fractured. 
     
     
       3. The connector connecting bolts of  claim 1 , wherein a bottom surface of the stepped recess on each of the connector connecting bolts has a diameter less than a diameter of the screw portion. 
     
     
       4. The connector connecting bolts of  claim 1 , wherein the stepped recess on each of the connector connecting bolts defines a smallest diameter of the respective bolt. 
     
     
       5. The connector connecting bolts of  claim 1 , wherein the auxiliary recess on each of the connector connecting bolts has a depth that is less than a depth of the stepped recess and larger than a depth of the seal groove. 
     
     
       6. The connector connecting bolts of  claim 1 , wherein a width of the auxiliary recess on each of the connector connecting bolts in the axial direction exceeds a width of the stepped recess in the axial direction. 
     
     
       7. The connector connecting bolts of  claim 1 , wherein a width of the seal groove on each of the connector connecting bolts in the axial direction and a depth of the seal groove in a radial direction are set so that a leading end of another one of the connector connecting bolts cannot contact a groove surface of the seal groove regardless of an alignment of the bolts. 
     
     
       8. The connector connecting bolts of  claim 1 , wherein a thickness of the flange on each of the connector connecting bolts in the axial direction and a width and depth of the seal groove measured respectively in the axial direction and the radial direction are set so that the flange of another connector connecting bolt cannot contact a groove surface of the seal groove of the bolt regardless of an alignment of the bolts. 
     
     
       9. The connector connecting bolts of  claim 1 , wherein a depth of the retaining groove on each of the connector connecting bolts is smaller than a depth of the seal groove. 
     
     
       10. A connector assembly, comprising:
 a connector including a tubular portion with a bolt insertion hole; and 
 a plurality of bolts, any one of the bolts is being insertable through the bolt insertion hole for connecting the connector assembly to a mating connector, each of the bolts comprising:
 a head at or near a first axial end part; 
 a screw portion at or near a second axial end part; 
 a flange bulging radially out adjacent to the head and being engageable with the connector when properly connected to prevent any further tightening of the bolt; 
 at least one stepped recess between the first axial end part and the screw portion, and being recessed radially inwardly a sufficient amount to be fractured when an excessive tightening torque is applied; 
 at least one retaining groove between the stepped recess and the screw portion in an axial direction and recessed radially inward; 
 at least one seal groove between the stepped recess and the flange in the axial direction and recessed radially inward, a width of the seal groove in the axial direction being less than a thickness of the flange in the axial direction so that the flange of one of the bolts cannot damage the seal groove of another of the bolts before either of the bolts is inserted into the bolt insertion hole, the connector assembly further comprising: 
 
 a retaining member mounted in the retaining groove and contacting the connector for preventing detachment of the bolt from the connector before connection of the connector assembly and the mating connector; and 
 at least one seal in the seal groove and held in close contact with the connector in a fluid-tight manner, wherein the bolt that is inserted through the bolt insertion hole is movable in the axial direction between an initial position before connection and a connection position after connection while penetrating through the bolt insertion hole and wherein an absence of damage to the seal groove ensures good sealing of the seal in the seal groove. 
 
     
     
       11. The connector assembly of  claim 10 , wherein the seal fit in the seal groove is exposed from one axial end opening edge of the tubular portion and the retaining member is in contact with another axial end opening edge of the tubular portion at the initial position. 
     
     
       12. The connector assembly of  claim 10 , wherein the seal is held in close contact with an inner peripheral surface of the tubular portion and the tubular portion is configured such that the flange is in contact with the one axial end opening edge of the tubular portion at the connection position. 
     
     
       13. The connector assembly of  claim 10 , wherein the connector is connectable to the mating connector by the screw portion of the bolt being rotated about an axis when a rotational force is applied to the head so that the mating connector is pulled toward the connector by a screwing of the screw portion. 
     
     
       14. A plurality of identical bolts, each of the bolts comprising:
 a head in proximity to a first axial end of the bolt; 
 a screw portion in proximity to a second axial end of the bolt that is spaced from the first axial end in an axial direction of the bolt; 
 a flange bulging radially out adjacent to the head; 
 at least one stepped recess between the first axial end and the screw portion, and being recessed radially inwardly a sufficient amount to fracture when a selected torque is applied; 
 a retaining groove between the stepped recess and the screw portion and recessed radially inward for receiving a retaining member; and 
 at least one seal groove between the stepped recess and the flange and recessed radially inward for receiving at least one seal, wherein a thickness of the flange in the axial direction is larger than a width of the seal groove in the axial direction so that the flange of one of the bolts is not insertable into the seal groove of another of the bolts for preventing damage to the seal groove. 
 
     
     
       15. The bolt of  claim 14 , further comprising at least one auxiliary recess adjacent an axial end of the stepped recess and between the stepped recess and the screw portion and recessed radially inward, the auxiliary recess being engageable by a jig if the stepped recess is fractured. 
     
     
       16. The bolt of  claim 15 , wherein a width of the auxiliary recess in the axial direction exceeds a width of the stepped recess in the axial direction.